Apparatus, system, and method

ABSTRACT

An apparatus is configured to determine an illumination condition for irradiating a printed product with light. The printed product is generated by outputting an image onto a recording medium based on fed input image data. The apparatus includes an input unit configured to receive inputs of luminance dynamic range information of the input image data and exposure condition information at the time of imaging regarding the input image data, an acquisition unit configured to acquire characteristic information of the recording medium, and a determination unit configured to determine the illumination condition based on the luminance dynamic range information, the exposure condition information, and the characteristic information.

BACKGROUND OF THE INVENTION Field of the Invention

The aspect of the embodiments relates to an information processingapparatus, an image processing system, a control system, and aninformation processing method for determining an illumination conditionfor irradiating a printed product on which an image is output.

Description of the Related Art

Conventionally, image processing apparatuses such as digital copyingmachines, printers, and facsimile machines using various printingmethods such as the inkjet method, the electrophotographic method, andthe thermal transfer method have been in widespread use. These imageprocessing apparatuses print an image onto a recording medium togenerate a printed product after performing image processing on inputimage data with use of an image processing unit provided inside theapparatus or software accompanying the apparatus (generally called aprinter driver if the image processing apparatus is the printer). Theimage processing performed as described above is performed assuming thatthe printed product is observed under a predetermined environment.Therefore, the printed product may be unable to appear in a colordesired by an observer under an environment different from the assumedenvironment.

Now, a specific example in the case of the inkjet printer will bedescribed. Generally, a color image to be output by the printer issubjected to a color design so as to allow the color image to match acolor gamut, such as standard red, green, and blue (sRGB), defined bythe international standards on a cathode-ray tube (CRT) or a liquidcrystal display, which is a display device. The sRGB color gamut isdefined under a luminance of 80 cd/m² and a color temperature of 5000Kon the CRT and the like. In the present disclosure, assume that theprinted product printed by the inkjet printer with the color imagematching this sRGB color gamut is desired to be observed under anenvironment of light equivalent to the luminance of 80 cd/m².Hereinafter, the light corresponding to the luminance of 80 cd/m² andthe color temperature of 5000K shall be referred to as “standardillumination”.

For such a reason, the printed product may be undesirably observed as acolor different from the designed desired color as described above whenthe printed product is observed under an illumination environment havinga luminance or a color temperature largely deviating from the standardillumination. To address such a situation, there is proposed a techniquefor generating a printed product observable as similar brightness and asimilar color to those under the standard illumination even under theobservation environment different from the above-described standardillumination.

Japanese Patent Application Laid-Open No. 2012-044475 discusses atechnique that switches a lookup table around the black color accordingto a luminance of a wall because a black region in an image becomesunintentionally prominent due to brightness (reflectance) of the wallopposite from an observation position. Further, Japanese PatentApplication Laid-Open No. 2016-054356 discusses measuring and holding adiffuse reflection component and a specular reflection componentindependently for each printing mode in advance, and predicting a changein a black density or color saturation according to a luminance of awall. Then, a printing mode for increasing the density or the colorsaturation is selected based on the above-described prediction.

In this manner, according to Japanese Patent Application Laid-Open No.2012-044475 and Japanese Patent Application Laid-Open No. 2016-054356,there is such a situation that the black density and the colorsaturation of the dark portion unintentionally reduce due to theobservation environment, and the printed product is not observed as thesimilar brightness and color to those when being observed under thestandard illumination. This situation can be improved by selecting aplurality of lookup tables prepared in advance or the printing mode.

As described above, Japanese Patent Application Laid-Open No.2012-044475 and Japanese Patent Application Laid-Open No. 2016-054356discuss the image processing technique for printing the printed productso as to allow the printed product to be observed under the similarcolor and brightness to those under the standard illumination even underan environment other than the standard illumination.

On the other hand, when data having a wide luminance dynamic range, suchas RAW data captured by a digital camera, is input to the printer as theinput image data, the input image data is subjected to such luminanceconversion processing that the image data is compressed within aluminance dynamic range that the printer can output. This means that,under the standard illumination, the printed product is observed by anobserver in a luminance dynamic range corresponding to a sum of theluminance dynamic range of the printed product and a luminance dynamicrange of the standard illumination with which the printed product isirradiated. However, even the addition of the luminance dynamic range ofthe standard illumination is insufficient to reproduce the wideluminance dynamic range held by the input image data, such as the RAWdata.

SUMMARY OF THE INVENTION

To address such a situation, the disclosure is directed to reproducingthe input image data having the wide luminance dynamic range, such asthe RAW data, in a further wide luminance range.

According to an aspect of the embodiments, an apparatus configured todetermine an illumination condition for irradiating a printed productwith light, the printed product being generated by outputting an imageonto a recording medium based on fed input image data, the apparatusincludes an input unit configured to receive inputs of luminance dynamicrange information of the input image data and exposure conditioninformation at the time of imaging regarding the input image data, anacquisition unit configured to acquire characteristic information of therecording medium, and a determination unit configured to determine theillumination condition based on the luminance dynamic range information,the exposure condition information, and the characteristic information.

Further features of the disclosure will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a block diagram illustrating a configuration of an imageprocessing apparatus. FIG. 1B is a block diagram illustrating aconfiguration of an image output apparatus.

FIG. 2 illustrates an example of a processing configuration of the imageprocessing apparatus and the image output apparatus.

FIG. 3A illustrates an image processing procedure.

FIG. 3B illustrates an example of a gamma curve.

FIG. 4 illustrates a general idea of luminance dynamic ranges forfacilitating better understanding thereof.

FIGS. 5A and 5B each illustrate a relationship between an inputluminance range and an output luminance range.

FIGS. 6A and 6B each illustrate a relationship between the inputluminance range and the output luminance range.

FIG. 7 illustrates a display unit presented to a user.

FIG. 8 is a flowchart illustrating a flow of processing according to afirst exemplary embodiment.

FIG. 9 illustrates processing for converting image data.

FIGS. 10A, 10B, and 10C each illustrate an example of a configuration ofa system that controls an illumination condition.

FIG. 11A is a flowchart illustrating processing according to a thirdexemplary embodiment. FIG. 11B is a flowchart illustrating processingaccording to a second exemplary embodiment.

FIG. 12 is a conceptual diagram illustrating a positional relationshipbetween a printed product and illumination.

FIG. 13 illustrates an example of a processing configuration of theimage processing apparatus and the image output apparatus.

FIG. 14 illustrates an example of a screen on which the user inputsobservation environment illumination.

FIG. 15 is a flowchart illustrating processing according to a fourthexemplary embodiment.

FIG. 16 illustrates an example of a screen on which the user configuressettings.

FIG. 17 illustrates conversion processing and a method for determiningthe illumination condition according to a fifth exemplary embodiment.

FIG. 18 illustrates a relationship between the input luminance range andthe output luminance range.

FIG. 19 illustrates a relationship between the input luminance range andthe output luminance range.

FIG. 20 illustrates an example of a screen presented to the user.

FIGS. 21A and 21B illustrate the Weber-Fechner law.

FIG. 22 illustrates an example of a method for presenting theillumination condition.

DESCRIPTION OF THE EMBODIMENTS

In the following description, an exemplary embodiment of the disclosurewill be described with reference to the drawings. In the followingdescription, candela (cd/m²) will be used as a unit of an intensity oflight, but the unit of an intensity of light is not limited thereto andlumen (lm) or lux (lx) may be used therefor.

FIG. 12 is a conceptual diagram illustrating a room 500 in crosssection. Room illumination 502 is installed on a ceiling 501. A printedproduct 504 output by an inkjet printer, which will be described below,is decorated on a wall 503. The room illumination 502 is the standardillumination corresponding to the luminance of 80 cd/m² and the colortemperature of 5000K. In the present disclosure, assume that the printedproduct output by the printer is subjected to a color design with a viewof being observed under the standard illumination. On the other hand,the printed product 504 can also be exhibited in combination of the roomillumination 502 and auxiliary illumination 505, as seen in a museum anda photo exhibition. A broken line in FIG. 12 indicates a general ideaabout how the auxiliary illumination 505 irradiates the printed product504. In this case, it is effective to change the printing mode accordingto an observation environment thereof with use of the techniquediscussed in the above-described patent literature, Japanese PatentApplication Laid-Open No. 2016-054356.

Now, a configuration of the present exemplary embodiment will bedescribed with reference to FIG. 4. As illustrated in FIG. 4, generally,a luminance dynamic range of input image data input from an imagingunit, such as a camera, is wider than a luminance dynamic range of aprinted product+illumination having a fixed illuminance. In this case,the input image data is subjected to processing for reducing theluminance range according to a luminance range of a recording mediumsuch as paper, which is a non-light emitting object. On the other hand,the present exemplary embodiment is directed to reproducing theluminance dynamic range of the input image data from a luminance dynamicrange of the printed product+illumination having a variable illuminanceby adjusting an illumination condition, such as using the auxiliaryillumination.

FIG. 1A illustrates an example of a configuration of an informationprocessing apparatus functioning as an image processing apparatus 100according to the present exemplary embodiment. A central processing unit(CPU) 104 executes an operating system (OS) and various kinds ofprograms stored in a read only memory (ROM) 105 and a storage unit 103with use of a random access memory (RAM) 106 as a work memory, therebycontrolling a configuration that will be described below via a systembus 109.

An input unit 101 is a serial bus interface, such as Universal SerialBus (USB). Then, an input device, such as a keyboard and a mouse, and animage input device, such as a memory card reader, a digital camera, anda scanner, are connected to the input unit 101. The CPU 104 inputs auser instruction, image data, and the like via the input unit 101, anddisplays a graphical user interface (GUI), an image, a processingprogress, a result, and the like on a display unit 102, which is amonitor.

The storage unit 103 is a recording medium storing various kinds ofprograms and various kinds of data therein, such as a hard disk drive(HDD) and a solid-state drive (SSD). The programs stored in the storageunit 103 include a program for realizing image processing that will bedescribed below.

A communication unit 107 is a network interface for connecting to awired or wireless network 110, such as Ethernet (registered trademark),Bluetooth (registered trademark), Wireless Fidelity (Wi-Fi), andpeer-to-peer (P2P). An output unit 108 is a serial bus interface, suchas USB, and outputs image data and the like to an image output apparatus111 or a memory card writer connected to the serial bus.

The CPU 104 communicates with a server apparatus and another computerapparatus in the network 110 via the communication unit 107. The CPU 104can receive various kinds of programs and data from the serverapparatus, the other computer apparatus, or the like in the network 110to perform processing, and provide data of a processing result to theserver apparatus or the other computer apparatus in the network 110.Computer apparatuses that the CPU 104 can communicate via thecommunication unit 107 also include the image output apparatus 111, andthe CPU 104 can also output the image data to the image output apparatus111.

The image processing apparatus 100 is realized by supplying the programfor realizing the image processing that will be described below to acomputer apparatus, such as a personal computer, a tablet, and asmartphone. In the case where the tablet or the smartphone is used asthe image processing apparatus 100, the input unit 101 and the displayunit 102 can be configured as a touch panel by being stacked on eachother.

FIG. 1B is a block diagram illustrating an example of a configurationwhen the inkjet printer is assumed to be employed as the image outputapparatus 111. A control unit 120 includes a CPU 120 a, such as amicroprocessor, and a RAM 120 b, a ROM 120 c, and the like as memories.The RAM 120 b, for example, temporarily stores therein various kinds ofdata such as the image data received from the image processing apparatus100 and generated recording data, along with being used a work area ofthe CPU 120 a. The ROM 120 c stores therein a control program of the CPU120 a and various kinds of data such as a parameter needed for arecording operation.

The control unit 120 performs processing for inputting/outputting thedata and the parameter used to record the image data and the likebetween the image output apparatus 111 and the image processingapparatus 100 via an interface 121. Further, the control unit 120performs processing for receiving inputs of various kinds ofinformation, such as a character pitch and a character type, from anoperation panel 122. Further, the control unit 120 outputs an ON signalor an OFF signal for driving a carriage motor 123 and a conveyance motor124 from a driver 126 via the interface 121. Further, the control unit120 outputs a discharge signal or the like to a driver 127, therebycontrolling driving for discharging ink from a recording head 125. Thecontrol unit 120 reads out the program stored in the RAM 120 b, by whicheach of the above-described processing procedures is realized.

FIGS. 1A and 1B illustrate an example of an image processing system inwhich the image processing apparatus 100 and the image output apparatus111 are configured as different apparatuses from each other, but theapplicability of the present exemplary embodiment is not limited to theabove-described configuration. The present exemplary embodiment may beapplied to an image forming apparatus in which the image processingapparatus 100 and the image output apparatus 111 are configured as anintegrated apparatus. For example, the present exemplary embodiment canbe applied to a system that introduces the configuration of the imageoutput apparatus 111 into the image processing apparatus 100 andcontrols the printer as so-called printer driver software. Further, thepresent exemplary embodiment can also be applied to, for example, animage copying apparatus including an image reading device.

FIG. 2 is a block diagram illustrating an example of a processingconfiguration of the image processing apparatus 100 and the image outputapparatus 111 illustrated in FIGS. 1A and 1B. The processingconfiguration illustrated in FIGS. 1A and 1B is realized by supplying aprogram for realizing this processing configuration and a functionthereof to the image processing apparatus 100 and the image outputapparatus 111 and executing this program.

The image data is input from the digital camera or the like via an imagedata input unit 201, and, at the same time, image data information, suchas information at the time of imaging, for example, exposure conditioninformation, and luminance dynamic range information, is input via animage data information input unit 202. A print luminance determinationunit 203 generates print data (output luminance data) for printing theimage data from the input image data and image data information. Thegenerated print data is transmitted to a print processing unit 204 inthe image output apparatus 111. Then, after the print data is subjectedto each processing procedure in the image output apparatus 111, aprinted product is output.

On the other hand, a recording medium characteristic acquisition unit205 of the image output apparatus 111 acquires characteristicinformation indicating a characteristic of the recording medium fromdata databased in advance, by the user's selecting the recording mediumto use. Then, the acquired characteristic data of the recording mediumis transmitted to an illumination condition determination unit 206 ofthe image processing apparatus 100. The illumination conditiondetermination unit 206 determines a needed illumination condition basedon a difference between the luminance dynamic range of the input imagedata and a luminance dynamic range of the print data that is calculatedby the print luminance determination unit 203, and the characteristicdata of the recording medium. A method for determining this illuminationcondition will be described in detail below. Then, an illuminationcondition presentation unit 207 presents the determined illuminationcondition to the user.

FIG. 3A illustrates image processing for outputting color input imagedata onto the recording medium when the image output apparatus 111 isassumed to be the inkjet printer. The print processing unit 204 of theimage output apparatus 111 receives image data (luminance data) of 8bits for each of red (R), green (G), and blue (B) colors, i.e., 256tones for each of them that is held by a commonly used image file, suchas Joint Photographic Experts Group (JPEG). After the image data issubjected to a plurality of processing procedures, the image outputapparatus 111 eventually outputs bit image data (recording data) of 1bit indicating whether to discharge an ink droplet for each of black(K), cyan (C), magenta (M), and yellow (Y). In the followingdescription, these processing procedures will be described.

First, the image processing apparatus 100 receives the input image dataexpressed by a luminance signal of 8 bits for each of the R, G, and Bcolors from the digital camera or the like. Then, the image processingapparatus 100 performs pre-color space conversion processing 301 on thereceived luminance signal data of R, G, and B. In the present example,the image processing apparatus 100 converts the luminance signal datainto R′, G′, and B′ data of 8 bits or 10 bits for each of the colorswith use of a three-dimensional lookup table (LUT). This pre-color spaceconversion processing 301 is performed to correct a difference between acolor space expressed by the input R, G, and B image data and a colorspace reproducible by the image output apparatus 111. More specifically,this processing is called color gamut (gamut) mapping processing, and aconversion from RGB to XYZ, which is a color space conversion, iscarried out and then a conversion from XYZ to R′G′B′ is carried outafter that, by which a color gamut held by the input data is convertedinto a color gamut reproducible by the printer. In this process, theluminance range held by the input data, i.e., a Y component in the XYZdata, is converted into a luminance range reproducible by the imageoutput apparatus 111. As a result, the luminance range expressible bythe image output apparatus 111 corresponds to the luminance range of theprinted product under the standard illumination. This luminance rangewill be described in detail below.

Next, the data of each of the R′, G′, and B′ colors subjected to thepre-color space conversion processing 301 and the luminance conversionprocessing at the same time as that is transmitted from the imageprocessing apparatus 100 to the image output apparatus 111. The imageoutput apparatus 111 performs color conversion processing 302 forconverting the data of each of the R′, G′, and B′ colors subjected tothe pre-color space conversion processing 301 into data of 10 bits foreach of K, C, M, and Y colors with use of a three-dimensional LUT. Inthe color conversion processing 302, the RGB-system image data of theinput system that is expressed by the luminance signal is converted, asa color conversion, into ink color data corresponding to ink of each ofK, C, M, and Y used by the image output apparatus 111.

Next, output γ processing 303 is performed on the ink color data of 10bits for each of the K, C, M, and Y colors subjected to the colorconversion processing 302 with use of a one-dimensional LUTcorresponding to each of the colors. FIG. 3B illustrates an example of agamma curve (S-shaped γ) used in the output γ processing 303. Normally,a linear relationship is not established as a relationship between thenumber of ink droplets (dots) supplied per unit area of the recordingmedium and a recording characteristic, such as a reflection densityacquired by measuring the recorded image. Therefore, an input tone levelof each of the four colors should be corrected so as to establish alinear relationship between the input tone level of 10 bits for each ofthe K, C, M, and Y colors and the density level of the image recordedaccording thereto. In other words, the γ processing aims to furtheraccurately reproduce the input image data when the printed product isoutput by the image output apparatus 111. Generally, a linearrelationship is not established between a result of the printed productand the input image due to the characteristic of the recording mediumeven if the input image data is processed by linear processing and isoutput in this state by the image output apparatus 111. This may raise anecessity of measuring the characteristic of the recording medium to beused in advance and designing a gamma curve that allows the input andthe output to have a more linear relationship therebetween.

Referring back to FIG. 3A, quantization processing 304, such as ditheror error diffusion processing (ED), is performed on the ink color datasubjected to the output γ processing 303. More specifically, the inkcolor data is converted from the data of 10 bits for each of the K, C,M, and Y colors into binary data of 1 bit for each of the colors thatindicates whether to discharge or not to discharge the ink droplet. Theink droplet is discharged from the recording head 125 based on theconverted binary data, and the printed product is output.

Next, a relationship between the input luminance range and the outputluminance range in the luminance conversion processing performed at thesame time as the pre-color space conversion processing 301 will bedescribed with reference to FIG. 5A. FIG. 5A illustrates therelationship in a case of an ideal example in which the input luminancerange is linearly converted into the output luminance range. If theoutput luminance range of the printed product can sufficiently expressthe luminance range of the input data, the conversion can beappropriately achieved just by converting the input into the output soas to produce an output linear with respect to the input as indicated bya solid line 1001 in FIG. 5A. However, generally, the luminance rangeexpressible by the printed product printed on the non-light emittingobject, such as the paper, under the standard illumination is narrowerthan the input luminance range. An output luminance on the paper, i.e.,a maximum luminance on paper white is determined by an intensity ofillumination with which the printed product is irradiated under anenvironment in which this printed product is observed. Generally, in thecase where the color design employed in the inkjet printer is the sRGBcolor space, the conversion processing is performed assuming that theluminance dynamic range is 0 to 80 cd/m². Therefore, if the luminancerange of the input image data falls within the range of 0 to 80 cd/m²,the input image data is subjected to such processing that the luminancerange is not changed thereby. However, for input image data having aluminance range exceeding that, the conversion processing should beperformed so as to allow the input image data to fall within the rangeof the luminance dynamic range expressible on an output side, i.e., onthe recording medium.

FIG. 5B illustrates normal processing, i.e., the conversion processingactually performed assuming that the printed product is observed underthe standard illumination, when the printed product is printed on therecording medium such as the paper. FIG. 5B illustrates an exampleindicating a luminance conversion (a gamma curve) for outputting inputimage data having a luminance dynamic range of 0 to 200% by the inkjetprinter. In this case, conversion processing curved like a solid line1003 is performed instead of a linear conversion like a broken line1002.

When the image is output on the recording medium such as the paper,which is the non-light emitting body, a maximum value of reflectance is100%. In the present example, a luminance on a white background(hereinafter referred to as a paper white region) of glossy paper isassumed to correspond to reflectance of 100%, and is defined to be 80cd/m² in the case of the above-described sRGB color space. Therefore,the luminance 80 cd/m² on the paper white region of the glossy papercorresponds to the reflectance of 100%. In the normal processingestablished assuming that the printed product is observed under thestandard illumination, the input image data having the dynamic range of0 to 200% is converted as indicated by the solid line 1003. Generally,so-called 18% gray reflectance, which is close to reflectance of a humanskin color, maintains a similar output luminance to the luminance of theinput image data. Therefore, a generally used gamma curve is designed insuch a manner that the solid line 1003 overlaps the broken line 1002 ina range of 0 to 18% like in FIG. 5B. Further, the shape of the curve canbe changed according to a designer's intention.

[Processing Method]

Next, a specific data processing method by the print luminancedetermination unit 203 in the image processing apparatus 100 will bedescribed. As described above, the present exemplary embodiment isdirected to reproducing an imaging scene, i.e., reproducing theluminance dynamic range of the input image data on the recording mediumby actively controlling the illumination condition when the printedproduct is observed. Therefore, the present exemplary embodiment isconstructed assuming that the luminance dynamic range of the input imageis wider than the dynamic range when the printed product is irradiatedby a standard light source of the luminance of 80 cd/m².

In the present exemplary embodiment, the image data input to the imagedata input unit 201 of the image processing apparatus 100 is RGB datagenerated by linearly developing RAW data handled by recent digitalcameras and the like. The RAW data is image data in an unprocessed statebefore the data is subjected to various kinds of processing andconverted into JPEG data inside the camera. Further, a luminance dynamicrange of the RAW data is wider than a luminance dynamic range of theJPEG data. Imaging information of the RAW data, such as an exposurecondition, is input to the image data information input unit 202 alongwith the input of the RAW data to the image data input unit 201. Thisinformation can be received as Exchangeable image file format (Exif)data of the digital camera. The Exif data includes the dynamic range ofthe image data, and an exposure state at the time of the imaging, i.e.,a so-called exposure compensation value. In the present exemplaryembodiment, the image data is assumed to have a negative value as theexposure compensation value, i.e., assumed to be underexposed imagedata.

As described above, the print luminance determination unit 203 convertsthe RGB luminance data, which is the input image data, from RGB to XYZ,and further converts the image data from XYZ to R′G′B′, therebydetermining a pixel value of each pixel.

FIGS. 6A and 6B each illustrate a relationship between the inputluminance dynamic range and the output luminance dynamic range in theluminance conversion processing according to the present exemplaryembodiment. First, supposing that the information input to the imagedata information input unit 202 is, for example, the RAW image datahaving the dynamic range of 0 to 200% and information meaning theexposure compensation value=−1, i.e., underexposure by one exposurevalue, the relationship in this case will be described. Now, if theimage is captured with the exposure compensation value set to −1, anoutput luminance is converted on the digital camera side so as to matcha half of the input luminance in a case of a correct exposure (i.e., ina case where the exposure compensation value is 0). Then, the converteddata is input to the printer. The data input at this time is dataconverted in such a manner that a luminance value at 200% in the inputluminance dynamic range reduces by half as indicated by a broken line1004 in FIG. 6A. In other words, the output luminance dynamic rangefalls within 100%.

Similarly, if the input image data is RAW image data having a dynamicrange of 0 to 400% and is captured with the exposure compensation valueset to −2, the output luminance is converted on the digital camera sideso as to match one-fourth of the input luminance. Then, the converteddata is input to the printer. The data input at this time is dataconverted in such a manner that a luminance value at 400% in the inputdynamic range reduces to one-fourth as indicated by a broken line 1005in FIG. 6A. In this case, the output dynamic range also falls within100%.

Therefore, in the case of any of the above-described two examples, theoutput luminance is converted so as to fall within the range of 0 to100% and is a luminance reproducible on the printer side, so that theluminance value does not have to be narrowed more than that.

On the other hand, if the input image data is the RAW image data havingthe luminance dynamic range of 0 to 400% and is information indicatingthe exposure compensation value=−1, i.e., underexposure by one exposurevalue, the input data is data in which the luminance value at 400% isconverted into a half. In this case, the output luminance dynamic rangeexceeds the luminance value range reproducible on the printer side.Therefore, the output luminance should be converted so as to fall withinthe range of 0 to 100% reproducible by the printer. A broken line 1007in FIG. 6B indicates data after the conversion on the printer side.

In the configuration according to the present exemplary embodiment, theprinted product is irradiated with light at an illuminance higher thanthe standard illumination assumed to provide the luminance of 80 cd/m²by using the auxiliary illumination. By this irradiation, the luminancesindicated by the broken line 1004 and the broken line 1005 in FIG. 6Aare raised to a luminance indicated by a solid line 1006, and theluminance indicated by the broken line 1007 in FIG. 6B is raised to aluminance indicated by a solid line 1008. Therefore, in the case of anyof the broken line 1004, the broken line 1005, and the broken line 1007,the printed product appears as an extremely dark image compared to theprinted product output by the normal processing illustrated in FIG. 5B,when the printed product output on the recording medium is observedunder the standard illumination.

In the above-described manner, the image processing apparatus 100receives the RAW data linearly developed on the imaging device side,such as the digital camera, and the information indicating the luminancedynamic range and the negative exposure compensation value, which is theexposure condition, as the information at the time of the imaging of theRAW data. Then, the image processing apparatus 100 performs theprocessing for converting the image data into the luminance dynamicrange expressible by the image output apparatus 111 based on thereceived information. The RAW data is used in the present exemplaryembodiment because the RAW data can be linearly processed, and, further,maintains the 18% gray image even when the printed product is irradiatedwith the auxiliary illumination, thus allowing the image of the imagingscene under the correct exposure to be reproduced. Further, the RAW datacontains the number of tones for one pixel as large as 12 bits to 16bits, and therefore may have an advantage of allowing the image to beacquired with smooth gradation and reduce deterioration of an imagequality even after being subjected to the image processing.

Next, processing for each type of the recording medium will bedescribed. As described above, the reflectance and the luminance valueon the paper white region of the glossy paper are assumed to be 100% and80 cd/m², respectively. However, the recording medium has lowerreflectance than the glossy paper depending on a surface condition ofthe used recording medium, and therefore the luminance value also fallsbelow 80 cd/m² on the paper white region having the reflectance of 100%.Examples thereof include less glossy mat paper and plain paper. Then, inthe present exemplary embodiment, assume that a luminance value on thepaper white region of the mat paper is 60 cd/m², and a luminance valueon the paper white region of the plain paper is 40 cd/m². A neededintensity of the auxiliary illumination is different depending on theluminance on the recording medium to compensate for insufficiencycorresponding to the luminance dynamic range of the input image data.This difference can be handled by saving data indicating what kind ofcondition should be used for the conversion in the storage unit such asthe ROM for each type of the recording medium in advance, and acquiringcorresponding data at a timing when the recording medium to be used isselected.

[Method for Determining Illumination Condition]

Next, a method for determining the illumination condition will bedescribed. As described above, the printed product printed by the imageoutput apparatus 111 has the narrower luminance dynamic range than theinput image data, and therefore appears as a dark image under thestandard illumination. To address this situation, the present exemplaryembodiment reproduces a luminance range substantially equivalent to theluminance dynamic range of the input image data with use of theauxiliary illumination in addition to the standard illumination.

Now, suppose that the printed product on the glossy paper is irradiatedwith the standard illumination of 80 cd/m². When the luminance dynamicrange of the input image data is 0 to 200%, the luminance dynamic rangein which the maximum value is 200% can be reproduced if the paper whiteregion of the printed product has twice the luminance of 80 cd/m², i.e.,160 cd/m². The present exemplary embodiment is constructed assuming thatthe printed product is irradiated with the standard illumination of 80cd/m², and therefore irradiates the printed product with 80 cd/m²corresponding to the insufficiency with use of the auxiliaryillumination. Due to this irradiation, the output luminance dynamicrange of the printed product to be observed is raised as indicated bythe solid line 1006 in FIG. 6A. Similarly, when the luminance dynamicrange of the input image data is 0 to 400%, the luminance dynamic rangein which the maximum value is 400% can be reproduced if the paper whiteregion of the printed product has four times the luminance of 80 cd/m²,i.e., 320 cd/m². Therefore, the output luminance dynamic range to beobserved is raised as indicated by the solid line 1006 by irradiatingthe printed product with 240 cd/m² corresponding to the insufficiencywith use of the auxiliary illumination.

Similarly, assume that the luminance on the paper white region under thestandard illumination, i.e., the luminance corresponding to thereflectance of 100% is 60 cd/m², when the same input image is output onthe mat paper. Then, 240 cd/m² is used to reproduce the luminancedynamic range of 0 to 400% held by the input image data. Therefore, theimage processing apparatus 100 presents the illumination condition tothe user so as to prompt the user to irradiate the printed product with240-60=180 cd/m² corresponding to the insufficiency with use of theauxiliary illumination. Similarly, assume that the luminance on thepaper white region under the standard illumination, i.e., the luminancecorresponding to the reflectance of 100% is 40 cd/m², when the sameinput image is output on the plain paper. Then, 160 cd/m² is used toreproduce the luminance dynamic range of 0 to 400% held by the inputimage data. Therefore, the image processing apparatus 100 presents theillumination condition to the user so as to prompt the user to irradiatethe printed product with 160−40=120 cd/m² corresponding to theinsufficiency with use of the auxiliary illumination. The illuminationcondition determined in this case is the insufficiency of the luminanceon the paper white region of the recording medium. In other words, thisillumination condition means that the insufficiency of the luminance onthe paper white region is this value, and notifies the user ofirradiating the printed product with the auxiliary illumination so as tocompensate for this insufficient luminance. The above-describedprocessing is performed by the CPU 104 described with reference to FIG.1A.

A wavelength band of the auxiliary illumination is assumed to besubstantially equivalent to the standard illumination in principle, andtherefore an intensity of the light with which the paper white region isirradiated can be considered as a sum of the standard illumination andthe auxiliary illumination. Further, in the present exemplaryembodiment, the auxiliary illumination having the variable illuminanceis used in addition to the standard illumination, which is observationenvironment illumination, as the method for controlling the illuminationcondition under which the printed product is irradiated. The presentexemplary embodiment can be configured to use one or more illuminationsource(s) having the variable illuminance, or can be configured to useonly the illumination having the variable illuminance without using thestandard illumination. Even in this case, the illumination condition iscalculated by a similar method.

[Method for Presenting Illumination Condition]

The luminance value of the auxiliary illumination calculated by theabove-described method for determining the illumination condition ispresented to the user (an operator). FIG. 7 illustrates an example ofthe auxiliary illumination condition displayed on the display unit 102illustrated in FIG. 1A.

A flow of the data processing described so far will be described withreference to a flowchart illustrated in FIG. 8. First, in step S101, theimage processing apparatus 100 analyzes the input image data (the RAWdata) and the input image data information, which is the information atthe time of the imaging. The input image data information needed at thistime is the “information indicating the luminance dynamic range” and the“exposure information (the exposure compensation value) at the time ofthe imaging”. Next, in step S102, the image output apparatus 111acquires the characteristic of the recording medium to be used in theprinting by the image output apparatus 111. This is the informationacquired by the recording medium characteristic acquisition unit 205illustrated in FIG. 2, and is selected from the data measured in advanceand stored in the storage unit such as the ROM 120 c. In the presentexemplary embodiment, this information is the luminance value on thepaper white region of the recording medium to be used in the printing.In step S103, the image processing apparatus 100 converts the luminancevalue of the input image data into the print luminance value. In thepresent exemplary embodiment, the image processing apparatus 100converts the linearly developed underexposed image into the data in theluminance range corresponding to the reflectance of 0 to 100% asdescribed with reference to FIGS. 6A and 6B. In step S104, the imageprocessing apparatus 100 determines the illumination condition forreturning the luminance range converted in step S103 to the luminancerange originally held by the input image data, i.e., the illuminationcondition needed to reproduce the luminance range of the input imagedata. Then, the image processing apparatus 100 presents the determinedillumination condition to the user. Lastly, in step S105, the imageoutput apparatus 111 discharges the ink from the recording head 125based on the recording data subjected to the above-described processing,thereby generating the printed product.

By the above-described processing, in the present exemplary embodiment,the image processing apparatus 100 calculates the illumination conditionunder which the printed product output by the image output apparatus111, such as the printer, should be irradiated, based on the informationindicating the luminance dynamic range of the input image data and theinformation regarding the exposure condition. As a result, the presentexemplary embodiment allows the image to be reproduced in the luminancedynamic range of the input image data that is wider than the luminancedynamic range of the printed product.

The conversion processing performed on the RAW image is not limited tothe linear conversion. Conversion processing to which a slight gammacurve is applied as indicated by a broken line 1009 in FIG. 9 can beperformed. By this processing, the luminance of the printed product israised as indicated by a solid line 1010. As described above, the linearconversion is carried out in the range of to 18% to maintain the 18%gray reflectance, and the conversion processing with the gamma curveapplied thereto is performed in a luminance range higher than that, inso-called the normal processing, which does not control the illuminationwith which the printed product is irradiated. On the other hand, sincethe present exemplary embodiment is constructed assuming that the outputluminance range is raised by controlling the illumination, theprocessing leading to a reduction in the luminance compared to when theabove-described linear conversion is carried out, i.e., the processingleading to generation of a darker image as the image is performed in therange of 0 to 18%.

In the first exemplary embodiment, the image processing apparatus 100 isconfigured to present the optimum illumination condition to the user(the operator) and cause the user to adjust the illumination based onthe presented condition, but the disclosure is not limited to thismethod. A second exemplary embodiment will be described as an example ofa control system that automatically adjusts the illumination conditionon an illumination apparatus side that exhibits the printed product,based on the illumination condition determined by the above-describedmethod.

FIGS. 10A to 10C are each a configuration diagram illustrating anexample thereof. The example illustrated in FIG. 10A is the followingmechanism. A printed product 401 is exhibited at a predeterminedposition on an exhibition illumination apparatus 400. Then, theauxiliary illumination condition determined by the above-describedmethod is transmitted from a control personal computer (PC) 403 to theexhibition illumination apparatus 400, and the printed product 401 isirradiated with set light from illumination 402. A broken line in thedrawing indicates a general idea about how the light is emitted from theillumination 402 to the printed product 401. Besides the method forchanging the illumination condition with use of the control PC 403, theadjustment of the illumination condition can be achieved by writing theillumination condition into a portable memory, such as a Secure Digital(SD) card, and equipping the exhibition illumination apparatus 400 sidewith a function of reading out that.

FIG. 10B illustrates a system in which a plurality of exhibitionillumination apparatuses is connected to a central control PC 410 viawireless communication, such as Wi-Fi, and the illumination conditionneeded for the printed product exhibited on each of the illuminationapparatuses is set from the control PC 410. Further, FIG. 10Cillustrates the following system. An encrypted code 420 indicating asymbolized illumination condition like a so-called barcode is printed onthe printed product itself. Then, when the printed product is mounted onthe exhibition illumination apparatus, a reading device built in theexhibition illumination apparatus reads out the encrypted code, and theillumination condition is automatically adjusted. In one embodiment, theencrypted code on the printed product is printed so as to be preventedfrom being easily visually recognized with use of transparent ink or thelike.

A third exemplary embodiment is a measure for expressing the printedproduct in High Dynamic Range (HDR) to deal with a current trend thatdisplay devices of cameras, liquid crystal televisions, and the likestart supporting HDR. In other words, the expression of the printedproduct in HDR as a printed exhibition product is realized by combiningthe illumination as an auxiliary method to reproduce the wide luminancedynamic range held by the input image data on the printed product on thepaper, which is the non-light emitting medium. Then, the third exemplaryembodiment will be described as an example in which the image processingapparatus switches an operation in the case where the printed product isexpressed in HDR by the adjustment using the auxiliary illumination orthe like and an operation in the case where only the standardillumination is used like the conventional technique.

FIG. 11A is a flowchart illustrating processing according to the presentexemplary embodiment, and is a flowchart in which steps S106 and S107are added to the above-described flowchart illustrated in FIG. 8. StepsS101 and S102 are similar to FIG. 8. In step S106, the image processingapparatus determines whether the input image data is data on which HDRimage processing should be performed based on the analysis result instep S101. If confirming that the image is the linearly developed RAWdata and is an image captured under the underexposure condition, i.e.,the exposure compensation value is a negative value in the analysis ofthe input image data in step S101, the image processing apparatus setsan HDR processing execution flag to ON. On the other hand, if the inputimage data is the normal JPEG data, the image processing apparatus setsthe HDR processing execution flag to OFF. The image processing apparatusdetermines whether to perform the HDR image processing based on the HDRprocessing execution flag set in this step, step S106. In a case wherethe execution flag is set to ON (YES in step S106), in step S103, theimage processing apparatus performs similar image processing to thefirst exemplary embodiment (hereinafter referred to as image processingA). In a case where the execution flag is set to OFF, i.e., the HDRimage processing is unnecessary (NO in step S106), the processingproceeds to step S107, in which the image processing apparatus performsthe conventional image processing described with reference to FIG. 5B(hereinafter referred to as image processing B). In the case where theimage processing A is performed in step S103, the adjustment of theillumination condition is performed, so that, in step S104, the imageprocessing apparatus determines the illumination condition and presentsthe determined illumination condition to the user. In step S105, theimage output apparatus outputs the image onto the recording mediumspecified by the user, based on the image data subjected to any of theimage processing A and the image processing B, thereby generating theprinted product.

FIG. 11B is a flowchart of processing corresponding to the exhibitionillumination apparatus described in the second exemplary embodiment, andstep S104 in FIG. 11A is replaced with step S108. This processing isprocessing for embedding the encrypted data indicating the illuminationcondition into the image data subjected to the image processing A forthe adjustment of the illumination condition. In step S105, the imageoutput apparatus outputs the image data with the illumination conditionembedded as the encrypted data therein onto the recording medium,thereby generating the printed product.

In the above-described manner, in the present exemplary embodiment, theimage processing apparatus automatically determines whether the HDRprocessing should be performed based on the input image data.

In the above-described exemplary embodiments, the illumination conditionis adjusted assuming that the printed product is observed under thestandard illumination of 80 cd/m². On the other hand, in a fourthexemplary embodiment, the user measures and acquires the illuminationcondition of the observation environment under which the printed productis observed. Then, the image processing apparatus presents theillumination condition under which the printed product should beactually irradiated with use of the acquired illumination condition ofthe observation environment.

FIG. 13 is a block diagram illustrating an example of a processingconfiguration of the image processing apparatus 100 and the image outputapparatus 111 according to the present exemplary embodiment. The mainconfiguration is similar to FIG. 2, but the image processing apparatus100 further includes an observation condition acquisition unit 208 inthe present drawing. The user measures brightness of the environmentunder which the user observes the printed product by a predeterminedmethod, and the observation condition acquisition unit 208 acquires avalue of the observation environment illumination that is a result ofthis measurement. FIG. 14 illustrates an example of a screen on whichthe user inputs the value of the observation environment illuminationthat is the result of the measurement. The method for measuring theobservation environment illumination by the user can be measurementusing a dedicated illuminance meter or can be simplified measurement ofthe illuminance using a smartphone camera that is provided as a freeapplication for the smartphone.

Then, the illumination condition determination unit 206 calculates theillumination condition, and the illumination condition presentation unit207 presents a result of this calculation to the user. In the presentexample, the illumination condition is calculated based on thedifference between the luminance dynamic range of the input image dataand the luminance dynamic range of the print data, the characteristicdata of the recording medium, and the value of the observationenvironment illumination acquired by the observation conditionacquisition unit 208. For example, if the value of the observationenvironment illumination acquired from the user is 70 cd/m² and theillumination condition needed to reproduce the input luminance dynamicrange is 320 cd/m², 320−70=250 cd/m² is presented as the neededillumination condition.

FIG. 15 is a flowchart illustrating a procedure of processing accordingto the present exemplary embodiment. This processing is similar to theprocessing described with reference to FIG. 8 according to the firstexemplary embodiment, except for step S109. In step S101, the imageprocessing apparatus 100 analyzes the input image data information. Instep S102, the image output apparatus 111 acquires the characteristic ofthe recording medium. Next, in step S109, the image processing apparatus100 acquires the observation environment illumination condition. Morespecifically, the observation environment illumination condition is theinformation indicating the brightness of the observation environmentillumination condition acquired by the observation condition acquisitionunit 208 illustrated in FIG. 13.

In the above-described manner, in the present exemplary embodiment, theimage processing apparatus 100 includes the acquisition unit thatacquires the illumination condition of the observation environment fromthe user, and determines the illumination condition under which theprinted product is irradiated based on the acquired value. Thisconfiguration allows the image processing apparatus 100 to determine theillumination condition optimum for the user's observation environment.

In a fifth exemplary embodiment, the user inputs an upper limit valuesettable as the auxiliary illumination with which the printed product isirradiated together with the brightness of the illumination of theobservation environment under which the printed product is observed.Then, the fifth exemplary embodiment is characterized in that the inputimage data is subjected to the gamma processing according to the upperlimit value of the illumination condition without being linearlyconverted, if the value of the auxiliary illumination calculated basedon the input image data exceeds the upper limit value acquired from theuser.

FIG. 16 illustrates an example of a screen on which the user configuressettings according to the present exemplary embodiment. In the presentexample, the user specifies the upper limit value of the brightness withwhich the auxiliary illumination to be used by the user can irradiatethe printed product, at the same time as setting the brightness of theillumination of the observation environment measured by the user thathas been described in the fourth exemplary embodiment. In the presentexemplary embodiment, an operation in a case where the upper limit valueof the auxiliary illumination is 160 cd/m² will be described.

Conversion processing and a method for determining the illuminationcondition according to the present exemplary embodiment will bedescribed with reference to FIG. 17. If the input image data has theluminance dynamic range of 0 to 200% and is the RAW image data capturedwith the exposure compensation value set to −1 (underexposure by oneexposure value), the printed product should be irradiated with the 80cd/m² as the auxiliary illumination in addition to 80 cd/m², which isthe brightness of the observation environment. Since the upper limitvalue of the auxiliary illumination is 160 cd/m², the printed productcan be irradiated with 80 cd/m². Therefore, the conversion processing isperformed as indicated by a broken line 1701, and the illuminationcondition is presented to the user so as to prompt the user to irradiatethe printed product with 80 cd/m² as the auxiliary illumination. As aresult, the linearly developed image can be reproduced in the luminancedynamic range of 0 to 200% held by the input data as indicated by asolid line 1702 in FIG. 17.

Similarly, supposing that the input image data has the luminance dynamicrange of 0 to 400% and is the RAW image data captured with the exposurecompensation value set to −2 (underexposure by two exposure values), anoperation in this case will be described now. The linearly developedimage can be reproduced in the luminance dynamic range of 0 to 400% heldby the input data if the printed product can be irradiated with 240cd/m² as the auxiliary illumination in addition to 80 cd/m², which isthe brightness of the observation environment. However, the auxiliaryillumination can irradiate the printed product only with the upper limitvalue 160 cd/m² at most. In this case, the input luminance dynamic rangeis reproduced within a possible range by irradiating the printed productwith 80 cd/m², which is the brightness of the observation environment,and 160 cd/m², which is the upper limit of the auxiliary illumination.In the present example, a gamma is applied to the input image datahaving the luminance dynamic range of 0 to 400% as indicated by a brokenline 1703 in the drawing. This is processing for adjusting the outputluminance dynamic range to 0 to 300% according to the brightness of 240cd/m² in total, and can raise the luminance range of the printed productirradiated with the illumination of 240 cd/m² in total as indicated by asolid line 1704. The condition is presented to the user so as to promptthe user to set 160 cd/m², which is the upper limit value of thebrightness of the auxiliary illumination, as illustrated in FIG. 16.

In any of the above-described cases, the conversion processing leadingto the reduction in the luminance compared to when the linear conversionis carried out is performed in the range where the luminance is 0 to18%, similarly to the above-described exemplary embodiments.

In the above-described exemplary embodiments, the conversion processingis performed on the input image data assuming that the illuminationcondition of the observation environment is adjusted, but a sixthexemplary embodiment will be described as a case that supports both whenthe illumination condition is adjusted and when the image is observedwithout the illumination condition of the observation environmentadjusted. More specifically, the input image data is linearly developedif the brightness of the illumination of the observation environment isdarker than predetermined brightness, and the input image data isdeveloped while the gamma is applied thereto if the brightness of theillumination of the observation environment is the predeterminedbrightness or brighter.

FIG. 18 illustrates a relationship between the luminance dynamic rangeswhen the printed product is irradiated with only the auxiliaryillumination with the standard illumination set to 0 cd/m², i.e., in acompletely dark room. In this case, the image cannot be observed withoutthe auxiliary illumination, which basically excludes the possibilitythat the printed product is irradiated with only the standardillumination. If the input image data has the luminance dynamic range of0 to 200% and the exposure compensation value is −1, conversionprocessing like a broken line 1801 is performed on the input image data.Then, the luminance range is raised as indicated by a solid line 1803due to the irradiation of the printed product with the auxiliaryillumination set to 160 cd/m².

Similarly, if the input image data has the luminance dynamic range of 0to 400% and the exposure compensation value is −2, conversion processinglike a broken line 1802 is performed on the input image data. Then, theluminance range is raised as indicated by a solid line 1803 due to theirradiation of the printed product with the auxiliary illumination setto 320 cd/m².

On the other hand, an operation in the case where the image can beobserved without the illumination condition adjusted will be described.Now, assume that the brightness of the standard illumination is 80 cd/m²similarly to the first exemplary embodiment. The present exemplaryembodiment is directed to reproducing the image having the high dynamicrange by adding the auxiliary illumination according to the luminancedynamic range of the input image data, but, at the same time, possiblecases include a lack of the irradiation with the auxiliary illumination,i.e., observing the image even when the image is irradiated with onlythe standard illumination. As described above, the linearly developedimage is observed as a dark image under the standard illuminationcompared to the image developed while the gamma is applied theretoassuming that the image is observed under the standard illumination.Therefore, in the present exemplary embodiment, if the standardillumination is equal to or more than 80 cd/m², the input image data isdeveloped while the gamma is applied thereto with importance also placedon the case in which the image is observed with use of only the standardillumination. If the standard illumination is lower than 80 cd/m², theinput image data is linearly developed assuming that the image isobserved while being irradiated with the auxiliary illumination. Then,even in the case where the processing for applying the gamma isperformed, i.e., even in the case where the input image data isdeveloped assuming that the image is observed without the illuminationcondition adjusted, the conversion processing is performed so as toreduce the luminance compared to when the image is linearly developedwith respect to the 18% gray reflectance in consideration of theobservation of the image with the illumination condition adjusted.

Which conversion should be employed as the characteristic of theluminance conversion between the input and the output, the linearconversion or the gamma conversion, is determined based on a thresholdvalue set to cd/m², which is the standard observation environmentdefined by sRGB described in the first exemplary embodiment, but thethreshold value is not limited to this brightness. Further, the presentexemplary embodiment has been described based on the example in whichthe input image data is developed while the gamma is applied thereto ifthe brightness of the standard illumination is the threshold value orbrighter, and the input image data is linearly developed if thebrightness of the standard illumination is darker than the thresholdvalue, but can be configured to carry out different gamma conversionsbetween when the brightness of the standard illumination is darker thanthe threshold value and when the brightness of the standard illuminationis the threshold value or brighter.

In a seventh exemplary embodiment, the brightness of the standardillumination is roughly set from a representative use case in advanceand the auxiliary illumination condition is set, when there is nomeasure for acquiring the brightness of the observation environment. Theilluminance for each of commonly seen environments is different for eachof them, as an office environment in Japan is 600 lx, an officeenvironment in Europe and the United States is 500 lx, a homeenvironment in Japan is 300 lx, and a home environment in Europe and theUnited States is 200 lx. When the unit of each value is converted intocandela (cd/m²), the office environment in Japan is approximately 200cd/m², the office environment in Europe and the United States isapproximately 170 cd/m², the home environment in Japan is approximately100 cd/m², and the home environment in Europe and the United States isapproximately 70 cd/m².

An operation in a case where the user selects the office environment inJapan as the observation environment will be described with reference toFIG. 19. As described above, the brightness of the illumination of theobservation environment is regarded as 200 cd/m². In the abovedescription, the reflectance on the paper when the printed product isirradiated by the standard light source of 80 cd/m² is defined to be100%, so that the output luminance has a range of 200÷80=250% when thebrightness of the standard illumination is 200 cd/m² as described above.

Then, if the input image data has the luminance dynamic range of 0 to400% and is the RAW image captured with the exposure compensation valueset to −2 (underexposure by two exposure values), conversion processingas indicated by a broken line 1901 in FIG. 19 is performed. Then, theprinted product is irradiated with 150% corresponding to theinsufficiency, i.e., 80÷100×150=120 cd/m² as the auxiliary illuminationin addition to 200 cd/m², which is the brightness of the observationenvironment, i.e., the output luminance of 250%. Due to thisirradiation, the luminance of the printed product is raised as indicatedby a solid line 1902, and the luminance dynamic range of 0 to 400% heldby the input data can be reproduced. At this time, the condition ispresented to the user so as to prompt the user to set 120 cd/m² as thebrightness of the auxiliary illumination as illustrated in FIG. 20.

Further, the above-described exemplary embodiments have been describedbased on the example in which the RAW data is input as the input imagedata and the image processing is performed with use of the exposurecompensation value in the Exif data as the imaging condition. The RAWdata is used for the following reason. If an original image expressesthe color by 8 bits for each of R, G, and B, i.e., 24 bits in total,this is insufficient when, for example, the image is combined, and aimsof the use of the RAW data also include, as one of them, avoiding imagedeterioration due to generation of a fraction and occurrence of arounding error when the image is combined. On the other hand, in recentyears, a concept of combining images with use of color data of 24 bitsor more has been proposed. This concept is called high dynamic rangerendering, and image formats capable of handling the color data of 24bits or more are collectively called High Dynamic Range Imaging (HDRI).One exemplary embodiment of the disclosure may be configured to use, forexample, JPEG-HDR data (capable of storing an image in 32-bit color atmost while maintaining compatibility with conventional JPEG) in the HDRIfile format developed by Dolby Laboratories, Inc. among them instead ofthe RAW data.

Further, the above-described exemplary embodiments have been describedbased on the example in which the input image data and the informationregarding the imaging condition are directly input from the imagingunit, such as the camera, to the printer, but are not limited to thisconfiguration. For example, one exemplary embodiment of the disclosurecan be configured to receive the input image data and the informationregarding the imaging condition from a storage medium, such as a memorycard.

Now, in some example, an image quality of an appearance of an exhibitionproduct (the printed product+the auxiliary illumination) to be observed,i.e., the luminance dynamic range felt by the observer in this case iskept the same even when the optimum illumination condition is set so asto have some range in consideration of a sensitivity of human eyes tothe light intensity, and this example will be described.

Generally, human five senses are proportional to a logarithm, and thisis known as the Weber-Fechner law (hereinafter referred to as the WFlaw). The WF law is expressed by the following equations (1) and (2),and a stimulus value that changes a perceived value by 1 can bediscriminated by the human sense:Δstimulus amount/stimulus amount=K, wherein K is a constant value  (1),andperceived amount=K×Log(stimulus amount)  (2).

Then, the sensitivity of human eyes to the light intensity also followsthis WF law. For example, a magnitude of a star in the night sky is oneexample thereof. Light intensities from a brightest first-magnitude starto a visible sixth-magnitude star are different from one another in sucha manner that the light intensity increases so as to be multiplied by afifth root of 100 (=2.512) every time the level increases by onemagnitude. In other words, there is a difference as large as 100 timesin the light intensity between the first-magnitude star and thesixth-magnitude star.

FIG. 21A is a table listing examples of numeral values indicating therelationship expressed by the equation (1) with use of these starmagnitudes as one example, and FIG. 21B is a graph graphicallyindicating the equation (2). In this example, the stimulus value is anumerical value indicating the light intensity. This table indicatesthat the human sense can discriminate a difference from a stimulus valueof 251.2 when the stimulus value is 100, and can discriminate adifference from a stimulus value of 1004.8 when the stimulus value is400. Further, in FIG. 21B, K is determined to be K=1.512 from the tableillustrated in FIG. 21A. As described above, the human sense candiscriminate the stimulus value that changes the perceived value by 1.The graph illustrated in FIG. 21B means that the human sense candiscriminate a light intensity corresponding to a stimulus value of 500(the perceived value is approximately 4) and a light intensitycorresponding to a stimulus value of 1850 (the perceived value isapproximately 5) from each other, but feels that light intensitiestherebetween are approximately the same. Further, this graph means that,regarding weaker light, the human sense can discriminate a stimulusvalue of 100 (the perceived value is approximately 3), and feels thatlight intensities corresponding to stimulus values of 100 to 500 areapproximately the same.

In the present example, the light of the stars in the night sky has beendescribed by way of example, but the value of K is different dependingon a condition, i.e., an surrounding environment even when the lightintensity is the same. The discriminable Δstimulus value is differentbetween a dark room and a bright room even when the same change in thelight is observed in each of them. This means that a range where lightis perceived as light of the same intensity is different depending onthe environment.

FIG. 22 illustrates an example of the method for presenting theillumination condition in consideration of the above-described humansensitivity. In one embodiment, by measuring the observation environmentillumination (in this case, the luminance on the paper white region ofthe printed product 504 irradiated with only the room illumination 502illustrated in FIG. 12) in advance, and inputting a value thereof, thismethod presents the upper limit value, the optimum value, and a lowerlimit value of the auxiliary illumination condition needed in additionto this observation environment illumination.

In the above-described manner, according to the WF law, a similar effectcan be provided to the observer even when the illuminance of theauxiliary illumination is set to a lower value than a theoretical value.This can also be said to be effective from the viewpoint of energysaving. As a specific method for determining the lower limit value, theoptimum value, and the upper limit value, the optimum value isdetermined from the input image data information as described in thefirst exemplary embodiment when the luminance of the observationenvironment illumination is measured and the value thereof is input. Inthis optimum value, the observation environment illumination is alreadytaken into consideration. Then, the upper limit value and the lowerlimit value can be calculated from the following equations (3) and (4):upper limit value=optimum value×coefficient 1  (3),andlower limit value=optimum value×coefficient 2  (4).

The coefficient 1 and the coefficient 2 are considered to changedepending on the value of the optimum value, but this change can behandled by determining in advance how large values these values shouldbe set to according to the value of the optimum value in an experimentconducted in advance, i.e., the condition of the observation environmentillumination. It is considered that a plurality of coefficients issupposed to be prepared according to the value of the optimum value.This means that a degree of human ability to visually recognize thelight intensity has some range. Then, these values can be databased andrecorded in the storage unit such as the ROM in advance.

The aspect of the embodiments allows the input image data having thewide luminance dynamic range, such as the RAW data, to be reproduced ina further wide luminance range by appropriately determining theillumination condition under which the printed product is irradiated.

While the disclosure has been described with reference to exemplaryembodiments, it is to be understood that the disclosure is not limitedto the disclosed exemplary embodiments. The scope of the followingclaims is to be accorded the broadest interpretation so as to encompassall such modifications and equivalent structures and functions.

This application claims the benefit of Japanese Patent Application No.2017-089640, filed Apr. 28, 2017, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. An apparatus configured to determine anillumination condition for irradiating a printed product with light, theprinted product being generated by outputting an image onto a recordingmedium based on fed input image data, the apparatus comprising: an inputunit configured to receive input of luminance dynamic range informationof the input image data and exposure condition information at a time ofimaging regarding the input image data; an acquisition unit configuredto acquire characteristic information of the recording medium; and adetermination unit configured to determine the illumination conditionbased on the luminance dynamic range information, the exposure conditioninformation, and the characteristic information.
 2. The apparatusaccording to claim 1, wherein the acquisition unit acquires thecharacteristic information based on information indicating a type of therecording medium on which the printed product is output.
 3. Theapparatus according to claim 1, wherein the determination unitcalculates the illumination condition with use of a luminance value on apaper white region that is indicated by the characteristic information.4. The apparatus according to claim 1, wherein the exposure conditioninformation is an exposure compensation value, and a value thereof isnegative.
 5. The apparatus according to claim 1, wherein the determinedillumination condition is information indicating a luminance on a paperwhite region of the recoding medium.
 6. The apparatus according to claim1, wherein the input image data is RAW image data or JPEG-HDR data. 7.The apparatus according to claim 1, wherein a luminance dynamic rangeindicated by the luminance dynamic range information is wider than aluminance dynamic range reproducible on the recording medium.
 8. Theapparatus according to claim 7, wherein the determined illuminationcondition is a condition for reproducing the luminance dynamic rangeindicated by the luminance dynamic range information by irradiating theprinted product with the light.
 9. The apparatus according to claim 1,further comprising a presentation unit configured to present informationregarding the determined illumination condition.
 10. The apparatusaccording to claim 9, wherein the printed product is observed by beingirradiated with light from observation environment illumination andlight from illumination having a variable illuminance, and wherein theinformation presented by the presentation unit is information regardingan illumination condition of the illumination having the variableilluminance.
 11. The apparatus according to claim 10, further comprisinga second acquisition unit configured to acquire information regardingthe observation environment illumination from a user, wherein thedetermination unit determines the illumination condition further basedon the information regarding the observation environment illumination.12. The apparatus according to claim 10, further comprising a thirdacquisition unit configured to acquire an upper limit value of theillumination condition realized by the illumination having the variableilluminance from a user, wherein the determination unit determines theillumination condition further based on the upper limit value.
 13. Theapparatus according to claim 1, further comprising a generation unitconfigured to generate output luminance data having a narrower luminancedynamic range than the luminance dynamic range of the input image data,based on the luminance dynamic range information and the exposurecondition information.
 14. The apparatus according to claim 13, whereinthe output luminance data is generated by linearly converting the inputimage data.
 15. The apparatus according to claim 13, wherein the outputluminance data is generated by linearly converting the input image datawith respect to a luminance value at which the luminance dynamic rangeof the input image data is equal to or less than 18% and converting theinput image data while applying a gamma with respect to a luminancevalue at which the luminance dynamic range of the input image data ishigher than 18%.
 16. A system comprising: the information processingapparatus according to claim 13; and an image output apparatusconfigured to generate the printed product based on the output luminancedata.
 17. A system comprising: an information processing apparatusconfigured to determine an illumination condition for irradiating aprinted product with light, the printed product being generated byoutputting an image onto a recording medium based on fed input imagedata, the apparatus comprising: an input unit configured to receiveinput of luminance dynamic range information of the input image data andexposure condition information at a time of imaging regarding the inputimage data; an acquisition unit configured to acquire characteristicinformation of the recording medium; and a determination unit configuredto determine the illumination condition based on the luminance dynamicrange information, the exposure condition information, and thecharacteristic information; and a control apparatus configured tocontrol illumination with which the printed product is irradiated, basedon the illumination condition determined by the determination unit. 18.The system according to claim 17, wherein the information processingapparatus and the control apparatus are wirelessly connected to eachother.
 19. A method for determining an illumination condition forirradiating a printed product with light, the printed product beinggenerated by outputting an image onto a recording medium based on fedinput image data, the method comprising: receiving inputs of luminancedynamic range information of the input image data and exposure conditioninformation at the time of imaging regarding the input image data;acquiring characteristic information of the recording medium; anddetermining the illumination condition based on the luminance dynamicrange information, the exposure condition information, and thecharacteristic information.
 20. The method according to claim 19,wherein the acquiring acquires the characteristic information based oninformation indicating a type of the recording medium on which theprinted product is output.